Recently there has been several customers asking about scum lines and the dirty feeling they give customers. Just take a look at this picture that one of my customers sent me, nobody wants this in their tub!
Now contrary to some (but not all) customers beliefs, the hot tub does not create this nastiness, we bring it into the tub ourselves! There are many that would like to blame the tub for the creation of this gunk, but really this stuff is biological and is brought in via soaps, lotions, oils, and detergents on our bodies and our swimwear. Because of this, foaming in a hot tub is closely associated with scum lines. So lets get specific into the cause and solutions to Scum Lines.
A gross thing happens when a hot tub gets used frequently. A film builds up on the water that is an accumulation of body oils, grease, and other human byproducts (yuck) that are washed off from bathers. Lotions, shampoos, and hair products all add to this problem. This film often accumulates and forms scum rings along the waterline of your spa and will eventually gum up your hot tub filters.
In the past, people would use soap to try and deal with the water gunk, but overuse of soaps (or surfactants) often leads to foaming and throwing the water chemistry out of whack. The pool industry then set out to develop a serviceable alternative that incorporated enzymes and could be added to the water to break down all the unwanted stuff in and on the water.
This project faced a few difficulties. First, the enzyme had to be in liquid form so that it could be quickly incorporated into the water, and the enzyme that was chosen for its ability to break down oils and greases (lipase enzyme) was not entirely shelf-stable in liquid form. This meant that the enzymes would break down in the bottle before it could ever be used.
The second problem was that doses of traditional sanitizers like chlorine or bromine would destroy the enzymes so a new form of enzyme-based products were developed that were shelf stable and able to work in the water along with bromine, chlorine, biguanide, ozone, or non-chlorine shocks. The enzymes now work in conjunction with these sanitizers and actually boost their performance. The enzymes are positively charged to attract oil, organic particles, and any unwanted byproducts in your spa and hot tub. They then bond to these contaminants and dissolve them away to be filtered out of the water.
What are the benefits of using hot tub enzymes?
Untreated contaminants build up quickly in hot tubs which have a relatively small area of water and high water temperatures. Using a hot tub enzyme treatment will break down the organic waste that can then be filtered out without gumming up the works. Left untreated, contaminants can clog filters and shorten their life cycle.
There are some added benefits to using enzymes in your spa water. Hot tub enzymes also help with chemical smells that traditional sanitizers may cause. It also breaks down any irritants in the water that may result in eye and skin irritation (usually urine forming chloramines with chlorine in the water). The water will also feel smoother on your skin because it breaks down minerals and keeps them from building up along the water line.
As an added bonus for anyone who’s earth-conscious, consumers will be glad to know that this product is biodegradable and the only active ingredient in them is all natural. Enzymes work very well in spas and hot tubs because the warm water helps to speed up the degradation process. The end product of the process are harmless, inert, and there are no residues to build up. It’s a great, natural way to boost your sanitation system.
So what can we do to get rid of scum lines? Well here is what you can do!
Keep Water Clean
The first line of defense is maintaining proper chemistry levels, regularly replacing your hot tub water, and properly sanitizing the liner itself. This means emptying and refilling your hot tub every 60-90 days and using a cleaner while it’s empty to help keep everything as hygienic as possible. If it’s a mild scum problem, you may use a wipe or cleaning system along the water line without having to empty it entirely.
One of the biggest sources of junky scum comes from bathers themselves. If you’re having continuous buildup problems in your spa, make sure you take a shower before you enter the soothing water of your hot tub. Want to know all of the stuff you collect on your skin and hair that can gunk up your water? Oil, dead skin cells, lotions, creams, deodorant, and hair products can all contribute to scummy H2O. If you take a few minutes to shower off before hand, you can get all that stuff down the drain instead of circulating in your spa water (and collecting on your liner).
Make sure you’re doing a regular shock treatment in your hot tub, particularly if you are heavy users of your hot tub. If scum constantly presents itself in your water, you might need to boost your sanitizer levels and weekly shock treatments are a great way to do that.
You should also maintain a regular cleaning schedule which includes draining and scrubbing down your acrylic liner with a non-foaming cleaner before refilling with new water.
If your scum is green, this is usually a sign that there is some kind of metal in your water. Copper, magnesium, or some other dissolved metal in the water often reacts with bromine and can leave behind a green residue. To help eliminate the problem? Try a pre-filter so that your fill water will have as little extra metal in it as possible and you won’t have to do as much post-fill adjusting.
If your scum has a bluish green tint to it, there’s a chance that there’s a problem with your filters. It could be clogged, torn, or just worn out. Remember: standard paper filters should be replaced entirely every 1 ½-2 years, depending on how well they’re maintained. Filters should be getting sprayed off and cleaned once a month to help ensure their effectiveness so that the water stays properly sanitized and has proper circulation.
If you have a brown/grey color scum presenting itself, it could be a mineral like iron reacting in your water. This could also be an indicator that your pH level is a little high and you should try using a pH decreaser. Try to keep it at the lower end of 7.2-7.4 for a few months.
Ryan & matt
These two authors have been in the spa industry many many years. Ryan grew up around hot tubs and his father, Dave, founded and owns TAB. He has been a part of the company since it started in 2006. Matt has been servicing and repairing hot tubs since 2011 and before that was a carpenter, so he's always been handy and intelligent. Together the whole world of spa and billiard questions can be answered!